This invention relates to processes for heat-treating amorphous metal alloys and to products produced thereby. More specifically, this invention relates to processes for heat-treating and magnetic annealing amorphous metal alloys to tailor the magnetic properties thereof for specific product applications.
A group of magnetic, amorphous metal alloys have recently become commercially available. These compositions and methods for producing them are described, for example, in U.S. Pat. No. 3,856,513 to Chen et al, U.S. Pat. No. 3,845,805 to Kavesh, and U.S. Pat. No. 3,862,658 to Bedell. Such alloys are presently produced on a commercial scale by the Allied Chemical Corp. and are marketed under the Metglas.RTM. trademark.
Amorphous metal alloys have been utilized, for example, as cutting blades, described in U.S. Pat. No. 3,871,836 to Polk et al, and as acoustic delay lines, described in U.S. Pat. No. 3,838,365 to Dutoit.
Berry et al, in U.S. Pat. No. 3,820,040 have described an electromechanical oscillator wherein the Young's modulus of elasticity of an amorphous alloy is varied as a function of applied magnetic field. The Berry patent describes tests in which the Young's modulus and frequency of oscillation of amorphous alloy elements are caused to vary by a process which includes magnetic annealing of amorphous alloys in both parallel and transverse magnetic fields.
The remanence ratio M.sub.r /M.sub.s of a magnetic material is a measure of the shape of its magnetic hysteresis loop and is indicative of the potential usefulness of that material in various magnetic devices. Prior art amorphous magnetic alloys have generally been characterized by a ratio M.sub.r /M.sub.s between approximately 0.4 and approximately 0.6.
It is well known that magnetic annealing may be utilized to control the magnetic properties of certain polycrystalline magnetic alloys; e.g., the Permalloys.